Soldiers from the Northern States' Union Army are sweating apprehensively in their dark blue woolen uniforms, this hot National Day weekend in the US state of Pennsylvania.
"Re-enactment" is the hobby that involves recreating famous historical events with contemporary clothing and other objects.
In the United States, it is not least about the decisive battles of the American Civil War, such as in this case the bloody battle of Gettysburg in 1863.
It is seen as one of the most crucial of the war, and ended on July 3, the day before US National Day.
Ever since then, Americans have been playing a variant of the battle.
Hear them reason about their hobby in the clip above, and see the gunpowder smoke fights from this year's battle.